yeah i would def buy one or two of these. a polyphonic homemade synth is something that needs to be done. very exciting. can you have the same waveshaping function as on the ms-20? so that you can feed a live external source/signal of a sample or whatever and manually tweak the waveshaping to fuck with the processed sound?

Do you think that having an MS20 ESP feature on a polysynth would be useful?

I guess with something like a hex-pickup guitar maybe it could be, but it seems like other processing is left best to mono and modular synths.

"I guess with something like a hex-pickup guitar maybe it could be, but it seems like other processing is left best to mono and modular synths."

Yea, I don't think that's really necessary here. Of course, you could run sounds through the filters... actually it would work as a four (or more) voice resonator filter, you could pan the filters and way you wanted and have indy LFOs for each one. I did this with a FVS1... it's cool.

Hi. The KORG MS-20 is mentioned as an alternative to the SEM. But how about the KORG Delta? it has some unusual designs and a very characteristic and good sound. It´s VCO is controlled from four pitch sliders 16', 8', 4', and 2'. Each of these harmonics is a square wave but can be turned into a saw wave. Useful and intuitive.

The VCF is a 24 dB/oct LP/BP/HP with resonance. I think its the only KORG with that filter. I wonder why KORG did´nt continue using this filter in the following synths; Mono/Poly, Polysix and Trident. Anyone who know how this VCF is compared to the KORG 35 VCF?

Hi. The KORG MS-20 is mentioned as an alternative to the SEM. But how about the KORG Delta? it has some unusual designs and a very characteristic and good sound. It´s VCO is controlled from four pitch sliders 16', 8', 4', and 2'. Each of these harmonics is a square wave but can be turned into a saw wave. Useful and intuitive.

The VCF is a 24 dB/oct LP/BP/HP with resonance. I think its the only KORG with that filter. I wonder why KORG did´nt continue using this filter in the following synths; Mono/Poly, Polysix and Trident. Anyone who know how this VCF is compared to the KORG 35 VCF?

I thinkt the reason why Korg didn't use that filter in their "true" polyphonics is that it's quite a big circuit. (AFAIK there is only one VCF in the Delta, but it's been a while since I've looked. Incidentally I have a Delta with broken VCF in the garret. I had bought this - broken - because I wanted to use the keyboard action for my PS3200 clone, but when I found it hat just a damaged filter, I decided I'd restore it some day.)

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

What's neato is that Tom Gamble turned me on to breadboarding stuff on a Perfboard. I spent maybe six months after that fooling around with filter circuits. At first I just kept seeing how far out of spec I could make the componant values and it still work, then I started adding germanium diodes to ground for clipping, or diode linearizing crap in the feedback of filters. (maybe even MOSFETs arranged as diodes, hard to remember, this was almost ten years ago)... The only thing I had ever gotten to work prior to those filters was a few distortion boxes I had built... (do you see the connection?) I remember it usually working out just fine to screw with stuff in the feedback loop.

I built one where I put a diode clipping section like that into an SEM type filter topology. I never made it into four poles though, that's pretty cool.

If you wanted to build a polysynth but NOT in the SEM style, then everything needs to be voltage controlled. I like this approach since it will keep costs down (1 knob for each parameter instead of 1 knob for each parameter x number of voices).

This is not problem for VCO, VCA and VCF which are more often than not completely voltage controlled (aside from the resonance but that's just a case of an additional VCA).

However, simple circuits for fully VC LFO's and ADSR's are hard to find. The best option (simplest, cheapest and smallest) I've seen are the PIC based ones from electric druid.

Of course there are some other considerations. Switching oscillator wave shapes could be addressed with some CMOS switches. Mixing the two oscillators into the VCF could be handled by an inverter and an additional VCA.

It would be great if the boards could be designed to accommodate either approach to building a polysynth. Additionally, if the boards were completely voltage controlled, the ambitious builder could create a system for storing/recalling presets.Last edited by widdly on Thu Aug 05, 2010 10:05 pm; edited 1 time in total

If you wanted to build a polysynth but NOT in the SEM style, then everything needs to be voltage controlled. I like this approach since it will keep costs down (1 knob for each parameter instead of 1 knob for each parameter x number of voices).

This is not problem for VCO, VCA and VCF which are more often than not completely voltage controlled (aside from the resonance but that's just a case of an additional VCA).

However, simple circuits for fully VC LFO's and ADSR's are hard to find. The best option (simplest, cheapest and smallest) I've seen are the PIC based ones from electric druid.

Of course there are some other considerations. Switching oscillator wave shapes could be addressed with some CMOS switches. Mixing the two oscillators into the VCF could be handled by an inverter and an additional VCA.

It would be great if the boards could be designed to accommodate either approach to building a polysynth. Additionally, if the boards were completely voltage controlled, the ambitious builder could create a system for storing/recalling presets.

That's precisely what the JH-4 was. Everything voltage controlled, and switching made with FETs and OTAs.

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

What envelope did you use? I'd be interested in a schematic if there is one available. Simple VC-envelopes are hard to find.

It's a LM13600-based VC envelope that I don't recommend because of offset issues. I was lucky with the 13600 specimens I've used, but with other 13600's you may run into trouble - I won't publish such a circuit.
What I recommend instead is the use of my 4-transistor cell I've used for the MOTM VC LAG, which in retrospect looks like a Class C version of the famous Blackmer VCA - or simply use a Blackmer (THAT) VCA.

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Another idea came up of a simplified version of this Polysynth. One could build a divided down machine, like a string machine. Sometimes thin sounds are desirable. It indeed results in warmth and nuances (but not more fat) to build up sounds from several thin layers. Just like a Rembrandt painting, or like keeping you warm in cold temperatures; several thin layers of garments gives more warmth than one thick!

Add top octave divider circuitry to the board and only one board would be needed. To make the sound a bit thicker, one could add a board per instrument layer/section; build a three section ensembler with one board for strings, one for brass and one for human voices. (2 VCO:s per board ofcourse). Advantages compared to other existing stringers/paraphonics/ensemble synths is that you can design it after your own taste.

1. You can choose a larger keyboard, (most stringers use four octaves).
2. Velocity, AT possible?
3. Choose whatever filters and presets you like. Like the FFF, which could be built so that all presets could be used independent simultaneously.
4. VCO architecture with indepenent simultaneous pitch range controls, like on KORG Delta. Wide range up to 6 octaves or so.
5. Multiple Trigger mode as an alternative to individual VCA EG:s per key as on Lambda.
6. Portamento.
Etc..

Certainly interesting on it's own, it's pretty far from what I intend to make.

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Certainly interesting on it's own, it's pretty far from what I intend to make.

JH.

Yes, as a final instrument it´s far from it and we could start an own thread about it. It would be an appropriate instrument to house JH phasers, choruses and FFF as built in devices. The polysynth board seem to be a good starting kit as it has so many options, therefore I posted it here.

As it´s the linear effect which is intended in this project, in what way is KORG´s VCO design to prefer in front of Yamaha´s?

Is it?
I like them both ...

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Right now I'm still in the final stage of the Subtle Chorus project (documentation and shipping).

Then I'll take a look what comes next. I don't know it myself, yet. I'll start drawing circuits for various proposed projects, and watch out which develops a life of its own.

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

What envelope did you use? I'd be interested in a schematic if there is one available. Simple VC-envelopes are hard to find.

It's a LM13600-based VC envelope that I don't recommend because of offset issues. I was lucky with the 13600 specimens I've used, but with other 13600's you may run into trouble - I won't publish such a circuit.
What I recommend instead is the use of my 4-transistor cell I've used for the MOTM VC LAG, which in retrospect looks like a Class C version of the famous Blackmer VCA - or simply use a Blackmer (THAT) VCA.

JH.

I've been planning a simple polysynth recently. One thing that really got me stuck was trying to find a simple VCAR EnvGen.
I couldn't find your 4-transistor cell anywhere on your site, maybe I'm looking in the wrong place... Would you share the schematic please?
Thanks.

1 Board = something like a MS-10, but with MS-20 filter and two envelopes

2 Boards = a voice with CS-80 architecture (each VCO has its own HPF and LPF!) - just talking about architecture - it's still the Korg filters.

4 Boards = a simple single-VCO polyphonic a la Oberheim Four Voice

8 boards = a very powerful Four Voice synth with Korg filters and CS-80 architecture

16 Boards = powerful 8-Voice polyphonic

etc.

Interesting?

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot vote in polls in this forumYou cannot attach files in this forumYou can download files in this forum

Please support our site. If you click through and buy from our affiliate partners, we earn a small commission.